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Mitsuaki Yamauchi Kosuke Yokoyama Naoki Aratani Hiroko Yamada Sadahiro Masuo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(40):14311-14316
Most azobenzene derivatives are utilized as well‐defined photoresponsive materials, but their emission properties have not been of great interest as they are relatively poor. Here, we report crystallization‐induced emission (CIE) based on the suppression of the photoisomerization of azobenzene derivatives. Although these molecules show negligible emission in solution, their microcrystals exhibit intense emission from the azobenzene moieties as a result of CIE. Upon rapid precipitation, fine particles with low crystallinity were kinetically formed and underwent CIE over time with a concomitant increase in crystallinity. Furthermore, we demonstrated “photocutting” of an emissive single crystal using a strong laser by a combination of CIE behavior and photomelting based on the photoisomerization of the azobenzene moiety. Our results regarding the CIE behavior of azobenzene derivatives in addition to their photoisomerization can provide a new platform for developing photoresponsive luminescent materials. 相似文献
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Seoyeon Choi Rahul Dev Mukhopadhyay Younghoon Kim In‐Chul Hwang Wooseup Hwang Suman Kr Ghosh Kangkyun Baek Kimoon Kim 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(47):17006-17009
Transient self‐assembling systems often suffer from accumulation of chemical wastes that interfere with the formation of pristine self‐assembled products in subsequent cycles. Herein, we report the transient crystallization of a cucurbit[8]uril‐based host‐guest complex, preventing the accumulation of chemical wastes. Base‐catalyzed thermal decarboxylation of trichloroacetic acid that chemically fuels the crystallization process dissolves the crystals, and produces volatile chemical wastes that are spontaneously removed from the solution. With such self‐clearance process, no significant damping in the formation of the crystals was observed. The morphology and structural integrity of the crystals was also maintained in subsequent cycles. The concept may be further extended to obtain other temporally functional materials, quasicrystals, etc., based on stimuli‐responsive guest molecules. 相似文献
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Cecilia Cerretani Hiroki Kanazawa Tom Vosch Jiro Kondo 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(48):17313-17317
DNA has been used as a scaffold to stabilize small, atomically monodisperse silver nanoclusters, which have attracted attention due to their intriguing photophysical properties. Herein, we describe the X‐ray crystal structure of a DNA‐encapsulated, near‐infrared emitting Ag16 nanocluster (DNA–Ag16NC). The asymmetric unit of the crystal contains two DNA–Ag16NCs and the crystal packing between the DNA–Ag16NCs is promoted by several interactions, such as two silver‐mediated base pairs between 3′‐terminal adenines, two phosphate–Ca2+–phosphate interactions, and π‐stacking between two neighboring thymines. Each Ag16NC is confined by two DNA decamers that take on a horse‐shoe‐like conformation and is almost fully shielded from the solvent environment. This structural insight will aid in the determination of the structure/photophysical property relationship for this class of emitters and opens up new research opportunities in fluorescence imaging and sensing using noble‐metal clusters. 相似文献